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Long-Duration Energy Storage using High-Density Hydro

Objective

As renewable energy deployment grows, grid operators face challenges in balancing intermittent generation from wind and solar. European policies like the REPowerEU Plan, Green Deal, and Net-Zero Industry Act emphasize the urgent need for scalable energy storage to support renewable integration and net-zero goals. Existing alternatives—such as lithium-ion batteries—offer short-duration storage (2-4 hours) and are subject to supply chain vulnerabilities and raw material dependencies, affecting their scalability. Traditional pumped hydro energy storage (PHES), while proven, has long permitting cycles, high CAPEX, and strict geographical requirements.

We have developed HD Hydro®, an innovative pumped hydro technology that unlocks energy storage on small hills instead of mountains. By utilizing a high-density fluid (HDF) that is 2.5x denser than water, HD Hydro® can store 4-16+ hours of energy in sites previously unsuitable for PHES, dramatically expanding the number of viable locations for pumped hydro projects. It is cost-effective, modular, and integrates seamlessly with grid infrastructure, making it a superior and scalable choice for LDES. HD Hydro® is attractive to utilities, renewable energy and independent power developers. We have made significant progress, including:

- TRL6 validation through a 500 kW demonstration project in Plymouth, UK.
- 20 patents across 11 families protecting our technology.
- Strong partnerships with industry leaders, universities, and investors.

With this project, we will:
- Optimize and demonstrate the HD Turbine technology, including lab testing, fluid dynamics validation, and component optimization.
- Finalize the manufacturing and scale-up strategy for a 5 MW prototype, leveraging advanced manufacturing methods.
- Advance to TRL8, positioning HD Hydro® for full-scale commercial deployment.

The EIC Accelerator grant will enable us to de-risk industrialization, strengthening Europe’s energy independence and net-zero transition.

Keywords

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Programme(s)

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Topic(s)

Calls for proposals are divided into topics. A topic defines a specific subject or area for which applicants can submit proposals. The description of a topic comprises its specific scope and the expected impact of the funded project.

Funding Scheme

Funding scheme (or “Type of Action”) inside a programme with common features. It specifies: the scope of what is funded; the reimbursement rate; specific evaluation criteria to qualify for funding; and the use of simplified forms of costs like lump sums.

HORIZON-EIC-ACC - HORIZON EIC Accelerator

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Call for proposal

Procedure for inviting applicants to submit project proposals, with the aim of receiving EU funding.

(opens in new window) HORIZON-EIC-2025-ACCELERATOR-02

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Coordinator

RHEENERGISE LIMITED
Net EU contribution

Net EU financial contribution. The sum of money that the participant receives, deducted by the EU contribution to its linked third party. It considers the distribution of the EU financial contribution between direct beneficiaries of the project and other types of participants, like third-party participants.

€ 2 499 999,00
Address
COLLECTIVE AUCTION ROOMS 5 7 BUCK STREET
NW1 8NJ LONDON
United Kingdom

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SME

The organization defined itself as SME (small and medium-sized enterprise) at the time the Grant Agreement was signed.

Yes
Region
London Inner London — West Camden and City of London
Activity type
Private for-profit entities (excluding Higher or Secondary Education Establishments)
Links
Total cost

The total costs incurred by this organisation to participate in the project, including direct and indirect costs. This amount is a subset of the overall project budget.

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